A couple of theories: - person clearly had meticulously planned the execution of the hit and exfiltration. Even leaving red herrings on his way out of the city (backpack full of Monopoly money). Yet clumsily keeps _all_ of the evidence that would implicate himself in this murder. Not to mention he is wandering about in public while a multi-state manhunt is underway with the full weight of alphabet soup agencies, and…
If you wanted to get caught then why not just stay at the crime scene or surrender a few days later? But maybe he knew it was inevitable so he spent his last few days living life normally.
Reportedly he is smart, so he probably knows the value of a good mystery.